The invention relates to an alternating propulsion type endoscope for moving an endoscope shaft along a canal-shaped cavity and to a continuous drive type endoscope.
Endoscopes have become an important aid in technology and above all in medicine to inspect canal-shaped cavities which otherwise are only accessible by considerable operations. Endoscopes are preferably used for examining the esophagus, the stomach, the duodenum from the stomach, the intestines from the anus, the urethra, the bladder and the ureter.
Such endoscopes are equipped at their leading end with a lighting means and with an optical system for visually detecting the area upstream of the cavity. The optical information detected at the leading end of the endoscope usually is either transmitted to the rear by means of fiber optics through the endoscope to its operating end or is detected by means of an optical sensor chip at the leading end, is guided to the rear via an electric line through the endoscope and is displayed on a screen. Moreover, also a transmission of information via radio from the leading end to the operating end is possible.
Furthermore, endoscopes usually comprise a working conduit, as it is called, through which various operating instruments can be introduced and operated. For instance, small forceps for taking tissue specimens, biopsy needles, heatable cutting wires, small scissors, coagulation electrodes or the like are introduced to carry out surgical measures on damaged tissue where necessary. Finally a fluid conduit for washing, and operating wires or fluid lines for bending the leading end of the endoscope in several directions are usually provided. These operating wires or fluid lines are in turn guided inside the endoscope shaft to the leading or distal end thereof.
For introducing and moving forward the endoscope shaft in the canal-shaped cavity to be inspected, DE 42 44 990 discloses a respective device. In this device a slip hose is moved along with the endoscope shaft during the forward movement of the endoscope shaft into a cavity and is slipped inside-out upon reaching the distal end so that the portion of the slip hose slipped inside-out is resting vis-à-vis the cavity wall. The advantage of this resting portion of the slip hose consists in the fact that damages of the cavity wall are reduced. Moreover, it has been assumed with this device that when applied in medical engineering, the pain for the patient can be significantly reduced due to the forward movement when the slip hose is resting relative to the intestinal wall.
However, recent examinations have shown that the principal reason for the pain during coloscopy is not the relative movement between the introduced endoscope shaft and the intestinal wall, but that the pain is mainly caused by pressing the distal end of the endoscope shaft against the curved outer wall of intestinal bends. (In this context, each of the terms curved outer wall and inner wall denotes the cavity wall lying further outside or inside with respect to a fictitious center of a cavity bend).
Therefore it is an object of the invention to realize an endoscope comprising a propulsion system of a simple design by which less pressure is exerted against the curved outer wall.